JP3096523B2 - Vehicle suspension system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle suspension system for optimally controlling a damping characteristic of a shock absorber.

[0002]

2. Description of the Related Art Conventionally, as a vehicle suspension device for controlling damping characteristics of a shock absorber, for example, Japanese Unexamined Patent Publication No.
What is described in 163011 is known.
This conventional vehicle suspension detects the sprung vertical speed and the relative speed between the sprung and unsprung, and when both have the same sign, the damping characteristic is made hard, and when both have different signs, the damping characteristic is made soft. The control of the damping characteristics based on the skyhook theory is performed independently for four wheels.

[0003]

However, in the above-described conventional apparatus, the above-described configuration has the above-described structure. Therefore, when the hardware characteristics are suitable when the vehicle body is moving in the bounce direction, For body movements coupled with bounce, roll and pitching, the body moment of inertia around the center of gravity of the center of the body is added to the sprung mass,
There is a problem that the damping force (control force) is insufficient and the steering stability is poor.

[0004] In addition, devices for controlling roll and pitch are also known. However, these devices are separately and independently controlled and require other sensors such as a steering sensor. It was also desired to simplify control and reduce the number of parts.

Further, in the damping characteristic control based on the skyhook theory, it is necessary to switch the damping characteristic by driving the actuator each time the sign of the sprung vertical speed and the sign of the relative speed are switched. Therefore, there has been a problem that control responsiveness is deteriorated, and the number of times of driving of the actuator is increased, thereby reducing durability.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned conventional problems, and provides a sufficient vibration damping property even when the vehicle body is tilted due to a moment of inertia, thereby improving the riding comfort and steering stability of the vehicle. A first object is to provide a vehicle suspension device that can be improved, and a second object is to provide a vehicle suspension device that can achieve simplification of the configuration, improvement in control responsiveness, and improvement in durability of the actuator.

[0007]

According to a first aspect of the present invention, there is provided a vehicle suspension system according to the present invention.
As shown in the claim correspondence diagram, a shock absorber b interposed between the vehicle body side and each wheel side and capable of changing the damping characteristic by the damping characteristic changing means a, and a vicinity of a position where each shock absorber b is provided A sprung vertical speed detecting means c for detecting a sprung vertical speed, a damping characteristic control means e having a basic control unit d for controlling a damping characteristic of each shock absorber b based on a control signal obtained from the sprung vertical speed. When the direction of the sprung vertical speed and the direction of the sprung vertical speed difference between the left and right sides of the vehicle are in the same direction, the product of the sprung vertical speed difference and the sprung vertical speed is provided in the damping characteristic control means e. A roll correction control unit f for controlling the damping characteristic of each shock absorber b based on a control signal obtained by adding the obtained correction rate to a control signal obtained from the sprung vertical velocity. .

In order to achieve the first object, a vehicle suspension system according to a second aspect of the present invention is interposed between a vehicle body side and each wheel side, and changes damping characteristics by damping characteristic changing means a. A possible shock absorber b, a sprung vertical speed detecting means c for detecting a sprung vertical speed near a position where each shock absorber b is provided, and each shock absorber based on a control signal obtained from the sprung vertical speed. b
And a damping characteristic control unit e having a basic control unit d for controlling the damping characteristic of the vehicle. The direction of the sprung vertical speed and the direction of the sprung vertical speed difference between the front and rear of the vehicle body are the same. At one time, the damping characteristic of each shock absorber b is controlled based on a control signal obtained by adding a correction rate obtained from the product of the sprung vertical speed difference and the sprung vertical speed to a control signal obtained from the sprung vertical speed. And a pitch correction control unit g.

According to a third aspect of the present invention, in order to achieve the second object, in addition to the above-described structure, the shock absorber has a variable damping characteristic on the extension side and a low damping characteristic on the compression side. The damping device is formed into a structure having three regions: a hard region on the expansion side, a hard region on the compression side that has variable attenuation characteristics and the expansion side is fixed at low attenuation characteristics, and a soft region on both the expansion and compression sides that has low attenuation characteristics. The characteristic control means controls the shock absorber in the extension hard region when the control signal is a positive value, and controls the shock absorber in the compression hard region when the control signal is a negative value, and when the control signal is 0. The shock absorber is controlled in the soft range.

[0010]

In the vehicle suspension system according to the present invention, when the sprung speed detecting means detects the sprung vertical speed near the position where each shock absorber is provided, the basic control unit of the damping characteristic control means The damping characteristic of each shock absorber is controlled based on the control signal obtained from the sprung vertical speed. When the direction of the sprung vertical speed and the direction of the sprung vertical speed difference between the left and right of the vehicle body are the same direction, the roll correction control unit obtains the product of the sprung vertical speed difference and the sprung vertical speed. The damping characteristic of each shock absorber is controlled based on a control signal obtained by adding the correction rate to a control signal obtained from the sprung vertical velocity. Therefore, a sufficient control force can be obtained not only for the bounce but also for the roll of the vehicle body.

Further, in the vehicle suspension device according to the second aspect,
When the sprung vertical speed in the vicinity of the position where each shock absorber is provided is detected by the sprung speed detecting means, the basic control section of the damping characteristic control means performs a control based on the control signal obtained from the sprung vertical speed. Thus, the damping characteristic of each shock absorber is controlled. When the direction of the sprung vertical speed and the direction of the sprung vertical speed difference between the front and rear of the vehicle body are the same direction, the pitch correction control unit obtains the product from the sprung vertical speed difference and the sprung vertical speed. The damping characteristic of each shock absorber is controlled based on a control signal obtained by adding the correction rate to a control signal obtained from the sprung vertical velocity. Therefore, a sufficient control force can be obtained not only for the bounce but also for the pitch of the vehicle body.

According to the second aspect of the present invention, when the control signal has a positive value, the shock absorber is controlled in the extension side hard region (the pressure side is fixed to a low attenuation characteristic), and when the control signal has a negative value. The shock absorber is controlled in the compression side hard region (the extension side is fixed to low damping characteristics), and when the control signal is 0, the shock absorber is controlled in the soft region. Therefore, the control signal based on the sprung vertical speed is used. When the relative speed between the sprung and unsprung parts has the same sign, the stroke side of the shock absorber at that time is controlled to a hard characteristic, and when the sign is different,
The same control as the damping characteristic control based on the skyhook theory, in which the stroke side of the shock absorber at that time is controlled to a soft characteristic, can be performed without detecting the relative speed between the sprung and unsprung parts, and Since no other sensors such as a steering sensor are required, the structure can be simplified, and the switching of the damping characteristic in the direction of the low damping characteristic is performed without driving the actuator. As compared with the damping characteristic control based on the above, the switching frequency of the damping characteristic is reduced, and the control response and the durability of the actuator can be improved.

[0013]

An embodiment of the present invention will be described with reference to the drawings. First, the configuration will be described. FIG. 2 is an explanatory view showing the configuration of the vehicle suspension system according to the embodiment of the present invention. The vehicle suspension device is interposed between the vehicle body and four wheels and is provided with four shock absorbers SA.
₁ , SA ₂ , SA ₃ , SA ₄ (when describing these four shock absorbers collectively, and when describing their common configuration, they are simply indicated as SA). ing. In addition, a vertical acceleration sensor (hereinafter, referred to as a vertical G sensor) 1 that detects vertical acceleration is provided near the position where each shock absorber SA is mounted on the vehicle body. At a position near the driver's seat, there is provided a control unit 4 that receives a signal from each sensor 1 and outputs a drive control signal to the pulse motor 3 of each shock absorber SA.

FIG. 3 is a system block diagram showing the above configuration. The control unit 4 includes an interface circuit 4a, a CPU 4b, and a drive circuit 4c. A signal is input. The interface circuit 4
In a, a low-pass filter for removing noise in a high-frequency range (30 Hz or more) from signals sent from the vertical G sensor 1 and an acceleration signal passing through the low-pass filter are integrated to calculate a sprung vertical velocity Vn. _{(Vn 1, Vn 2, Vn} 3, V
There is provided a filter circuit 6 composed of a low-pass filter for conversion to n ₄ ).

FIG. 4 is a sectional view showing the structure of the shock absorber SA.
A is a cylinder 30, a piston 31 that defines the cylinder 30 in an upper chamber A and a lower chamber B, an outer cylinder 33 in which a reservoir chamber 32 is formed on the outer periphery of the cylinder 30, a lower chamber B and a reservoir chamber 32. Base 34 and piston 31
A guide member 35 for guiding the sliding of the piston rod 7 connected to the outer cylinder 33, a suspension spring 36 interposed between the outer cylinder 33 and the vehicle body, and a bump rubber 37.

FIG. 5 is an enlarged sectional view showing a portion of the piston 31. As shown in FIG. 5, the piston 31 has through holes 31a and 31b formed therein, and A pressure-side damping valve 20 and an extension-side damping valve 12 for opening and closing 31a and 31b, respectively, are provided. A stud 38 that penetrates the piston 31 is screwed and fixed to a bound stopper 41 screwed to the tip of the piston rod 7, and the stud 38 bypasses the through holes 31a and 31b. Communication for forming flow paths (extension-side second flow paths E, expansion-side third flow paths F, bypass flow paths G, and compression-side second flow paths J to be described later) that communicate the upper chamber A and the lower chamber B. A hole 39 is formed.
An adjuster 40 for changing the flow path cross-sectional area of the flow path is rotatably provided in 9. Also, stud 38
The communication hole 3 is formed on the outer periphery of the communication hole 3 in accordance with the direction of fluid flow.
An expansion-side check valve 17 and a compression-side check valve 22 that allow and shut off the flow on the flow path side formed by 9 are provided. Note that the adjuster 40 is provided with the pulse motor 3
Is rotated through the control rod 70 (see FIG. 4). Also, studs 38
A first port 21, a second port 13, a third port 18, a fourth port 14, and a fifth port 16 are formed in this order from the top.

On the other hand, the adjuster 40 has a hollow portion 19, a first horizontal hole 24 and a second horizontal hole 25 communicating between the inside and the outside, and a vertical groove 23 formed in the outer peripheral portion. I have.

Therefore, between the upper chamber A and the lower chamber B, a through-hole 31 is formed as a flow path through which fluid can flow during the extension stroke.
b, the inside of the extension side damping valve 12 is opened to open the lower chamber B
, The second port 13, the vertical groove 23,
Via the second port 13, the vertical groove 23, and the fifth port 16 via the fourth port 14, the outer peripheral side of the extension side damping valve 12 is opened to open the outer peripheral side of the extension side damping valve 12 to reach the lower chamber B, Then, the extension side check valve 17 is opened to open the extension side third flow path F to the lower chamber B, and the bypass to the lower chamber B via the third port 18, the second horizontal hole 25, and the hollow portion 19. There are four flow paths G. In addition, as a flow path through which a fluid can flow during the pressure stroke, the pressure side first valve that opens the pressure side damping valve 20 through the through hole 31a.
Channel H, hollow portion 19, first lateral hole 24, first port 21
, The pressure-side second flow path J that opens the pressure-side check valve 22 to reach the upper chamber A through the air passage, and the bypass flow that reaches the upper chamber A through the hollow portion 19, the second horizontal hole 25, and the third port 18. Road G
And three flow paths.

That is, the shock absorber SA is configured so that the damping characteristic can be changed in multiple steps by rotating the adjuster 40 with the characteristics shown in FIG. 6 on both the extension side and the compression side. That is, as shown in FIG. 7, a state where both the extension side and the compression side are soft (hereinafter, the soft area S
When the adjuster 40 is rotated in the counterclockwise direction from S), the damping characteristic can be changed in multiple stages only on the extension side, and the compression side becomes a region fixed to the low attenuation characteristic (hereinafter referred to as the extension side hard region HS). Conversely, when the adjuster 40 is rotated clockwise, the attenuation characteristic can be changed in multiple stages only on the compression side, and the expansion side becomes a region fixed to the low attenuation characteristic (hereinafter referred to as a compression side hard region SH). I have.

FIG. 7 shows the KK section, LL section, MM section, and NN section in FIG. 8, 9 and 10 and the damping force characteristics at each position are shown in FIGS.

Next, the operation of the control unit 4 for controlling the driving of the pulse motor 3 will be described with reference to the flowchart of FIG. This control is performed separately for each shock absorber SA.

Step 101 calculates a bounce signal V _BA , a roll signal V _RO , and a pitch signal V _PI as described below. FIG. 16 is a time chart showing changes in the sprung vertical speeds Vn ₁ and Vn ₂ and the roll signals _{FR VRO} and _{FL VRO at} the front wheel left and right positions, and FIG. 17 is a time chart showing the front wheel right and rear wheel right positions. 6 is a time chart showing changes in sprung vertical speeds Vn ₁ and Vn ₃ and pitch signals _{FR VPI} and _{RR VPI} . Each sprung mass vertical velocity _{Vn (Vn 1, Vn 2,} Vn 3, Vn 4) is in the upward direction a positive value, given respectively negative value in the downward direction.

(Bounce signal V _BA ) Front wheel right _FR V _BA = Vn ₁ front wheel left _FL V _BA = Vn ₂ rear wheel right _RR V _BA = Vn ₃ rear wheel left _RL V _BA = Vn ₄ (roll signal V _RO ) front wheel Right _FR V _RO = Vn ₁ -Vn ₂ Front wheel Left _FL V _RO = Vn ₂ -Vn ₁ Rear wheel Right _RR V _RO = Vn ₃ -Vn ₄ Rear wheel Left _RL V _RO = Vn ₄ -Vn ₃ (Pitch signal V _PI ) front right _FR V _PI = Vn ₁ -Vn ₃ front left _FL V _PI = Vn ₂ -Vn ₄ rear wheel right _RR V _PI = Vn ₃ -Vn ₁ rear wheel left _RL V _PI = Vn ₄ -Vn ₂ step 102 , Based on the following formula, the roll determination signal A (A ₁ , A ₂ , A ₃ ,
A ₄ ) That is, in this step, the conjunction phase on each spring vertical velocity Vn and the roll signal V _RO is determined whether phase (region indicated by oblique lines or network line in FIG. 16) or reverse phase, calculates the value of the roll component Is what you do.

Front wheel right A ₁ = Vn ₁ × _{FR VRO} front wheel left A ₂ = Vn ₂ × _{FL VRO} rear wheel right A ₃ = Vn ₃ × _{RR VRO} rear wheel left A ₄ = Vn ₄ × _{RL VRO} step 103 is a step of determining whether the roll determination signal a is a positive value (in-phase phase of sprung mass vertical velocity Vn and the roll signal V _RO), the process proceeds to step 104 in YES (phase), NO The process proceeds to step 105 in (reverse phase).

In step 104, the roll components V _R ( _FR V _R , _FL V _R , _RR V _R , _RL V _R ) of each wheel are represented by A (A ₁
, A ₂ , A ₃ , A ₄ ).

[0026] Step 105, the roll component V _R at each wheel _{(FR V R, FL V R} , RR V R, RL V R) which is a step of setting to zero.

In step 106, the roll judgment signal B (B) of the vehicle at each wheel position is calculated based on the following equation.
₁ , B ₂ , B ₃ , B ₄ ). That is,
In this step, it is determined whether the phase of each sprung vertical velocity Vn and each pitch signal _VPI is the same phase (the area shown by oblique lines or mesh lines in FIG. 17) or the opposite phase, and the value of the pitch component is calculated. It is.

Front wheel right B ₁ = Vn ₁ × _{FR VPI} front wheel left B ₂ = Vn ₂ × _{FL VPI} rear wheel right B ₃ = Vn ₃ × _{RR VPI} rear wheel left B ₄ = Vn ₄ × _RL V _PI step 107 is a step of determining whether the pitch determination signal B is a positive value (sprung mass vertical velocity Vn phase with the phase of the pitch signal V _PI), the process proceeds to step 108 in YES (phase), NO The process proceeds to step 109 in (reverse phase).

[0029] Step 108, the pitch component V _P of the wheels _{(FR V P, FL V P} , RR V P, RL V P) and B (B ₁
, B ₂ , B ₃ , B ₄ ).

[0030] Step 109, the pitch component V _P of the wheels _{(FR V P, FL V P} , RR V P, RL V P) and a step of setting to zero.

Step 110 is a step for judging whether or not the sprung vertical speed Vn is a positive value (the shock absorber SA is in the extension stroke). If YES (extension stroke), the process proceeds to step 111; The process proceeds to step 112 in (pressing stroke).

Step 111 is a step for obtaining a control signal V ( _FRV , _FLV , _RRV , _RLV ) on the extension stroke based on the following equation. Front right _{FR V = α 1 · Vn 1} + β 1 · FR V R + γ 1 · FR
V _P front wheel left _{FL V = α 1 · Vn 2} + β 1 · FL V R + γ 1 · FL
V _P rear wheel right _{RR V = α 2 · Vn 3} + β 2 · RR V R + γ 2 · RR
V _P rear wheel left _{RL V = α 2 · Vn 4} + β 2 · RL V R + γ 2 · RL
V _{P Note, α 1, β 1, γ} 1 , each proportional constant alpha ₂ of the front wheel, beta _2, gamma ₂ denote each proportional constant of the rear wheel.

In each equation, the portion bounded by the first α ₁ and α ₂ is the bounce rate, and β ₁ and β ₂
The rolled part is the roll rate, γ ₁ , γ ₂
The pitched portion is the pitch rate.

Step 112 is a step for obtaining a control signal V ( _FRV , _FLV , _RRV , _RLV ) on the pressure stroke side based on the following equation. Front right _{FR V = α 1 · Vn 1} -β 1 · FR V R -γ 1 · FR
V _P front wheel left _{FL V = α 1 · Vn 2} -β 1 · FL V R -γ 1 · FL
V _P rear wheel right _{RR V = α 2 · Vn 3} -β 2 · RR V R -γ 2 · RR
V _P rear wheel left _{RL V = α 2 · Vn 4} -β 2 · RL V R -γ 2 · RL
_VP step 113 is a step of determining whether or not control signal V is a positive value (upward), YES (upward)
Proceeds to step 114, and proceeds to step 1 when NO (downward).
Go to 15.

Step 114 is a step for judging whether or not the previous control signal V _-1 is a negative value. YES
The process proceeds to step 116 with NO, and proceeds to step 117 with NO. That is, in this step, it is determined whether or not the direction of the control signal V has been reversed.

Step 116 is a step of initially setting the threshold value V _S1 of the upward control signal V to a predetermined value.

Step 117 is a step for judging whether or not the control signal V has become _{equal to} or more than a predetermined threshold value V _S1.
Proceed to 19.

Step 118 is a step of updating the initially set threshold value V _S1 to the value of the control signal V at that time.

[0039] Step 119 target position Pn of the extension side of the shock absorber _{SA (FR Pn, FL Pn,} RR Pn, RL Pn) was calculated based on the following equation, towards this calculated target position Pn This is a step of driving the pulse motor 3.

Front wheel right _FR Pn = (P _{+ MAX} / _VS1 ) × _FRV front wheel left _FL Pn = (P _{+ MAX} / _VS1 ) × _FLV rear wheel right _RR Pn = (P _{+ MAX} / _VS1 ) × _RR V rear wheel left _RL Pn = (P _{+ MAX} / V _S1 ) × _RL V Step 115 is a step for determining whether or not the previous control signal V _-1 is a positive value.
Proceed to 20 and proceed to step 121 with NO. That is, in this step, it is determined whether or not the direction of the control signal V has been reversed.

Step 120 is a step of initially setting the threshold value V _S2 of the downward control signal V to a predetermined value.

In step 121, the absolute value of the control signal | V
Is a step of determining whether or not | is equal to or greater than the absolute value of a predetermined threshold | V _S2 |
And proceeds to step 123 with NO.

Step 122 is a step of updating the initially set threshold value V _S2 to the value of the control signal V at that time.

[0044] Step 123, the target position Pn of the compression side in the shock absorber SA based on the following equation _{(FR Pn, FL Pn, RR} Pn, RL Pn) is calculated, and pulse toward the calculated target position Pn This is a step of driving the motor 3.

The front wheel right _{FR Pn = (P -MAX / V} S2) × FR V front wheel left _{FL Pn = (P -MAX / V} S2) × FL V rear wheel right _{RR Pn = (P -MAX / V} S2) × _RR V rear wheel left _{RL Pn = (P -MAX / V} S2) × RL V or more and completes one control flow, thereafter those repeating the above control flow.

Next, the operation of the embodiment will be described with reference to the time chart of FIG. In the drawing, the control signal V, the damping force F and the relative speed, the control direction (stroke) of the shock absorber SA, and the target position Pn are shown in order from the top.
The pressure side alternately moves, and the peak values P ₁ and P _{2 change} in the vertical direction so as to exceed the threshold values V _S1 and V _S2 of the initial set values, respectively.

In the figure, a region a is a region where the control signal V is upward and less than the initial threshold value V _S1 . In this case, the maximum attenuation position P is determined by the value of the initial threshold value V _S1.
In order to reach _{+ MAX} , the target position P on the extension side that is the target
n will be controlled in proportion to the control signal V.

[0048] The next area b, the control signal V is an area to become the initial threshold V _S1 or reaches a peak value P _1, in this case, the teeth by the flow from step 117 of FIG. 14 118 As a result of performing the process of making the threshold value V _S1 coincide with the control signal V at any time, the extension-side target position Pn is held at the extension-side maximum attenuation position P _{+ MAX} until the peak value P ₁ is reached.

In the next area c, the control signal V has a peak value P _1.
From the time when the direction of the control signal V is reversed.
In this case, at the time when the control signal V becomes the peak value P _1, since the threshold V _S1 is also equal to the peak value P _1, on the basis of the calculation formula shown in step 119 of FIG. 14, the control signal V There When lower than the peak value P _1, so that the target position Pn of the extension side from that point decreases in proportion to the decrease of the control signal V.

The next region d is a region from when the direction of the control signal V is reversed to when it becomes _{equal to} or more than the initial downward threshold value V _S2 . In this case, the target position Pn on the pressure side is controlled in proportion to the control signal V so that the maximum attenuation position P- _MAX is obtained at the value of the initial threshold value V _S2 .

The next area e is an area until the control signal V reaches the peak value P ₂ after the control signal V becomes equal to or more than the initial threshold value V _S2 , and in this case, it follows the flow of steps 121 to 122 in FIG. As a result of performing the process of matching the threshold value V _S2 with the control signal V as needed, the target position Pn is held at the pressure-side maximum damping position P- _MAX until the peak value P ₂ is reached.

In the next area f, the control signal V has a peak value P ₂
From the time when the direction of the control signal V is reversed.
In this case, when the control signal V reaches the peak value P ₂ , the threshold value V _S2 is equal to the peak value P _2. Therefore, based on the arithmetic expression shown in Step 123 of FIG.
When the control signal V is upward changes than the peak value P _2, so that the target position Pn of the extension side from that point decreases in proportion to the change of the control signal V.

In the time chart of FIG.
The region g is a state where the control signal V based on the control signal V is reversed from a negative value (downward) to a positive value (upward),
At this time, the relative speed is still a negative value (shock absorber S
Since the stroke A is a pressure stroke side), at this time, the shock absorber SA is controlled to the extension side hard region HS based on the direction of the control signal V. Therefore, in this region, The pressure stroke side, which is the stroke of the shock absorber SA, has soft characteristics.

An area h is an area where the control signal V remains at a positive value (upward) and the relative speed is switched from a negative value to a positive value (the stroke of the shock absorber SA is extended). Therefore, at this time, the shock absorber SA is controlled to the extension side hard region HS based on the direction of the control signal V, and the stroke of the shock absorber is also the extension stroke. The extension stroke, which is the stroke of the absorber SA, has hardware characteristics proportional to the value of the control signal V.

Area j is a state where the control signal V is reversed from a positive value (upward) to a negative value (downward).
At this time, the relative speed is still a positive value (shock absorber S
Since the stroke A is the extension stroke side), at this time, the shock absorber SA is controlled to the compression-side hard region SH based on the direction of the control signal V. Therefore, in this region, The extension stroke side of the shock absorber SA has soft characteristics.

The region k is a region where the control signal V remains negative (downward) and the relative speed changes from a positive value to a negative value (the stroke of the shock absorber SA is on the extension stroke side). At this time, the shock absorber SA is controlled to the compression-side hard area SH based on the direction of the control signal V, and the stroke of the shock absorber is also the compression stroke,
Therefore, in this area, the shock absorber SA at that time is
The pressure stroke side, which is the stroke of the above, has hardware characteristics proportional to the value of the control signal V.

As described above, in this embodiment, when the control signal V based on the sprung vertical velocity and the relative speed between the sprung and unsprunged parts have the same sign (area h, area k), the shock at that time is determined. Damping characteristic control based on the skyhook theory, in which the stroke side of the absorber SA is controlled to hard characteristics, and when the sign is different (region g, region j), the stroke side of the shock absorber SA at that time is controlled to soft characteristics. Will be performed without detecting the relative speed between the sprung and unsprung portions. Further, in this embodiment, when shifting from the area g to the area h and from the area j to the area k, the attenuation characteristic is switched without driving the pulse motor 3.

As described above, in this embodiment, the following effects can be obtained. Since sufficient control force can be generated not only for bounces but also for pitches and rolls, a vehicle suspension system with excellent ride comfort and steering stability can be provided.

In performing the damping characteristic control based on the skyhook theory in consideration of the roll and pitch as described above, only the upper and lower G sensors are used as the detecting means, so that the number of parts can be reduced and the cost can be reduced. At the same time, labor and time for assembling, assembling space, and weight can be reduced.

Since the frequency of switching of the damping characteristic is reduced as compared with the damping characteristic control based on the conventional skyhook theory, the control responsiveness can be improved and the durability of the pulse motor 3 can be improved.

Although the embodiment has been described above, the specific configuration is not limited to this embodiment, and any change in the design without departing from the gist of the present invention is included in the present invention.

For example, in the embodiment, the control content is such that the stroke for controlling to the hardware characteristic side is determined depending on whether the sprung vertical speed is a positive value or a negative value, but a predetermined threshold is set for the sprung vertical speed. While the sprung vertical speed is within the positive and negative thresholds, the control is performed in the soft region SS in which both the expansion side and the compression side have soft characteristics, and when the positive and negative thresholds are exceeded, the hard characteristic (extension) is set. It is also possible to control to the side hard region HS or the compression side hard region SH) side.

In the embodiment, the target position is obtained based on the arithmetic expression. However, the target position may be obtained based on a map as shown in FIG. In this figure, (a) is a map for the expansion side, (b) is a map for the compression side, and the target position P corresponding to the value of the control signal V is shown.
n is set.

The bounce signal V _BA , roll signal V _RO , and pitch signal V _PI can also be obtained based on the following formula.

(Example 1 of bounce signal V _BA ) Front wheel right / left _FR V _BA , _FL V _BA = (Vn ₁ + Vn ₂ ) / 2 Rear wheel right / left _RR V _BA , _RL V _BA = (Vn ₃ + Vn ₄ ) / 2 (Bounce signal V _BA other example 2) Front / rear wheel right / left V _BA = (Vn ₁ + Vn ₂ + Vn ₃ + Vn ₄ )
/ 4 (Roll signal V _{RO and} other examples) Right wheel front / rear _FR V _RO , _RR V _RO = (Vn ₁ + Vn ₃ ) / 2
(Vn ₂ + Vn ₄ ) / 2 Left wheel front / rear _FL V _RO , _RL V _RO = (Vn ₂ + Vn ₄ ) / 2−
(Vn ₁ + Vn ₃ ) / 2 (Other examples of pitch signal V _PI ) Front wheel right / left _FR V _PI , _FL V _PI = (Vn ₁ + Vn ₂ ) / 2−2
_{(Vn 3 + Vn 4) /} 2 rear wheel right, left, _{RR V PI, RL V PI =} (Vn 3 + Vn 4) / 2-
(Vn ₁ + Vn ₂ ) / 2 In this embodiment, when one side of both the extension and compression strokes is controlled to the high damping characteristic side, the reverse stroke side is fixed to a predetermined low damping characteristic. Although a shock absorber having a structure is used, a shock absorber having a structure in which both extension and compression strokes change simultaneously can be used.

In this embodiment, the control signal is obtained based on the bounce rate, the pitch rate, and the roll rate.
Alternatively, the control signal can be obtained based on the bounce rate and the roll rate.

[0067]

As described above, the first aspect of the present invention is as follows.
When the direction of the sprung vertical speed and the direction of the sprung vertical speed difference between the left and right sides of the vehicle body are the same direction, the vehicle suspension described in the above describes a correction obtained from the product of the sprung vertical speed difference and the sprung vertical speed. Equipped with a roll correction control unit that controls the rate based on a control signal that is added to the control signal obtained from the sprung vertical speed, so that not only bounces, but also sufficient damping of the body roll due to steering operation This has the effect of improving ride comfort and steering stability.

Further, in the vehicle suspension device according to the present invention, when the direction of the sprung vertical speed and the direction of the sprung vertical speed difference between the front and rear of the vehicle body are the same, the sprung vertical speed difference and the spring Equipped with a pitch correction control unit that controls based on a control signal obtained by adding the correction rate obtained from the product of the upper and lower speeds to the control signal obtained from the sprung upper and lower speeds. Sufficient vibration damping can be obtained even for the pitch of, whereby the effect of improving the riding comfort and steering stability can be obtained.

According to a second aspect of the present invention, in addition to the above configuration, each of the shock absorbers includes an extension-side hard region in which the extension side has a variable damping characteristic and the compression side has a fixed low-amplitude characteristic.
The compression side is formed into a structure having three regions, a compression side hard region in which the compression side has a variable attenuation characteristic and the extension side is fixed to the low attenuation characteristic, and a soft region in which both the extension side and the compression side have a low attenuation characteristic. When the signal is above the positive threshold, the shock absorber is controlled in the extension hard region, and when the control signal is below the negative threshold, the shock absorber is controlled in the compression hard region, and the control signal is positive / negative. Since the shock absorber is controlled to be in the soft range when the threshold value is set, the damping characteristic control based on the Skyhook theory can be performed without using the relative speed detecting means. Cost reduction, assembling time,
The installation space and weight can be reduced, and the frequency of switching of the damping characteristics can be reduced as compared with the damping characteristics control based on the conventional skyhook theory, so that the control response can be improved and the damping characteristics switching actuator can be improved. The effect is that the durability of the device can be improved.

[Brief description of the drawings]

FIG. 1 is a conceptual view of a claim showing a vehicle suspension system of the present invention.

FIG. 2 is an explanatory diagram illustrating a configuration of a vehicle suspension device according to an embodiment of the present invention.

FIG. 3 is a system block diagram showing a vehicle suspension device according to the embodiment.

FIG. 4 is a cross-sectional view showing a shock absorber applied to the embodiment device.

FIG. 5 is an enlarged sectional view showing a main part of the shock absorber.

FIG. 6 is a damping force characteristic diagram corresponding to a piston speed of the shock absorber.

FIG. 7 is a characteristic diagram of a damping characteristic corresponding to a step position of a pulse motor of the shock absorber.

FIG. 8 is a perspective view of the shock absorber shown in FIG.
It is -K sectional drawing.

FIG. 9 is a perspective view of the shock absorber shown in FIG.
It is an L sectional view and MM sectional view.

FIG. 10 is a sectional view taken along line NN of FIG. 5 showing a main part of the shock absorber.

FIG. 11 is a damping force characteristic diagram when the shock absorber is on the extension side hard.

FIG. 12 is a damping force characteristic diagram of the shock absorber in a soft state on an extension side and a compression side.

FIG. 13 is a damping force characteristic diagram of the shock absorber in a pressure-side hard state.

FIG. 14 is a flowchart illustrating a control operation of a control unit in the embodiment device.

FIG. 15 is a time chart showing a control operation of a control unit in the embodiment device.

FIG. 16 is a time chart illustrating a method of determining a roll occurrence state in the apparatus according to the embodiment.

FIG. 17 is a time chart illustrating a method of determining a pitch occurrence state in the apparatus of the embodiment.

FIG. 18 is a map showing another example of how to obtain a target position.

[Explanation of symbols]

 a damping characteristic changing means b shock absorber c sprung vertical speed detecting means d basic control part e damping characteristic control means f roll correction control part g pitch correction control part

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-5-169958 (JP, A) JP-A-3-276807 (JP, A) JP-A-4-81315 (JP, A) 42319 (JP, A) JP-A-1-119440 (JP, A) JP-A-4-169314 (JP, A) JP-A-4-169313 (JP, A) JP-A-3-104726 (JP, A) JP-A-3-42320 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B60G 17/015

Claims (3)

(57) [Claims] 1. A shock absorber interposed between a vehicle body side and each wheel side and capable of changing damping characteristics by damping characteristic changing means, and detecting a sprung vertical speed near a position where each shock absorber is provided. A sprung vertical speed detecting means, a damping characteristic control means having a basic control unit for controlling a damping characteristic of each shock absorber based on a control signal obtained from the sprung vertical speed, a spring provided in the damping characteristic control means, When the direction of the upper and lower speed and the direction of the sprung vertical speed difference between the left and right of the vehicle body are the same direction, the correction rate obtained from the product of the sprung vertical speed difference and the sprung vertical speed was obtained from the sprung vertical speed. A vehicle suspension device comprising: a roll correction control unit that controls a damping characteristic of each shock absorber based on a control signal added to the control signal. 2. A shock absorber interposed between a vehicle body side and each wheel side and capable of changing damping characteristics by damping characteristic changing means, and detecting a sprung vertical speed near a position where each shock absorber is provided. A sprung vertical speed detecting means, a damping characteristic control means having a basic control unit for controlling a damping characteristic of each shock absorber based on a control signal obtained from the sprung vertical speed, a spring provided in the damping characteristic control means, When the direction of the upper and lower speeds and the direction of the sprung vertical speed difference between the front and rear of the vehicle body are the same direction, the correction rate obtained from the product of the sprung vertical speed difference and the sprung vertical speed was obtained from the sprung vertical speed. A vehicle suspension system comprising: a pitch correction control unit that controls a damping characteristic of each shock absorber based on a control signal added to the control signal. 3. A compression-side hard region in which the extension side has a variable attenuation characteristic and the compression side is fixed to a low attenuation characteristic, a compression-side hard region in which the compression side has a variable attenuation characteristic and the extension side is fixed to a low attenuation characteristic. The damping characteristic control means is formed in a structure having three regions of a soft region having a low damping characteristic on both the side and the pressure side, and the damping characteristic control means controls the shock absorber in the extension side hard region when the control signal is a positive value. 2. The system according to claim 1, wherein when the signal is a negative value, the shock absorber is controlled in a pressure side hard region, and when the control signal is 0, the shock absorber is controlled in a soft region.
Or the vehicle suspension device according to claim 2.